TORONTO — A spike in new COVID-19 cases in Ontario on Monday was attributed to two recent outbreaks — one at a farm in Windsor-Essex and another linked to a nail salon in Kingston.

But public health officials said the province's caseload remained steady despite the gradual reopening of the economy.

Dr. Barbara Yaffe, the province's associate medical officer of health, said the latest outbreaks in Windsor and Kingston — which account for more than 200 cases combined — illustrated the continued need for caution.

"This serves as an important reminder for why we are asking people and businesses to remain vigilant," she said. "As we relax public health measures, it is essential that all Ontarians continue to follow our public health advice."

Ontario reported 257 new cases of COVID-19 on Monday and seven new deaths related to the virus. The total number of cases now stands at 34,911, including 30,196 cases marked as resolved and 2,665 deaths.

The province reopened parts of its economy on June 12, with the Greater Toronto Area and some border communities reopening on June 24.

Only Leamington and Kingsville, Ont., remain in Stage 1 because of six farm outbreaks in those communities. 

On Monday, public health officials in Windsor-Essex asked for additional resources to deal with those outbreaks after more than 180 workers tested positive over the weekend. All of the cases are linked to a single farm.

Dr. Wajid Ahmed, the region's medical officer of health, said the spike in new cases followed increased testing of farm workers.

"It was expected that the testing initiative will identify positive cases among the farm workers, but we are clearly seeing the numbers going up in that sector," Ahmed said. "Almost all of the workers at the time of testing reported no symptoms."

Of the region's 88 new cases reported on Sunday, 87 were agri-food workers. On Monday, 96 of 98 positive tests were from that sector.

While Windsor-Essex does not specify if the workers are local residents or temporary foreign workers, Ahmed has previously said that 90 per cent of the cases are among migrant workers.

Premier Doug Ford said Monday the province is bolstering resources in the region to help stop the spread of the virus.

"I don't think it's contained to one farm, to be very frank," he said. "It's just a full out onslaught down there to nip this in the bud."

Last week, Ontario announced a three-point plan to address COVID-19 outbreaks on farm, including the introduction of on-site testing.

Ford said Monday farm testing will be expanded to other areas of the province where agriculture sector outbreaks have been reported.

"We're going to do the same in Niagara (and) other farming communities," he said. "We have to protect the people."

Hundreds of migrant workers across the province have tested positive for the virus and three have died.

Health officials have said cramped living and worker quarters continue to contribute to the spread of COVID-19.

Approximately 20,000 migrant workers come to Ontario each year to work on farms and in greenhouses — many of them from Mexico, Guatemala and the Caribbean.

Ahmed said he and the health unit's CEO spent the weekend putting out calls for help to bolster local contact tracing resources.

A dozen workers from neighbouring health units have been temporarily seconded to Windsor-Essex to help, he added.

"With the additional staffing support from the other neighbouring health units ... our team of nurse practitioners, public health nurses, and public health inspectors will be on site to do health assessments on all these workers who tested positive," he said. 

Advocacy group Justice for Migrant Workers called for the shutdown of the province's entire agri-food sector until every workplace can be fully sanitized and safety measures put in place to protect workers.

Meanwhile, five more people tested positive for COVID-19 in the outbreak linked to a nail salon in Kingston, Ont.,  bringing the total to 27 confirmed cases.

"We all have to learn from this nasty, slippery, sneaky virus that can spread very quickly from person-to-person in these settings," said Dr. Kieran Moore, medical health official for the region.

He said most of the cases related to the outbreak were showing minimal symptoms and no one had been hospitalized. 

The outbreak at the nail salon last week promoted the City of Kingston to make wearing a face mask mandatory in all indoor public places.

Mayors in the Greater Toronto and Hamilton Area asked the provincial government on Monday to make non-medical mask use mandatory in large urban centres.

"We are at a critical time in the fight against COVID-19," the mayors said in a statement. "We must do everything we can to avoid flare-ups of the virus in our communities."

— with files from John Chidley-Hill

This report by The Canadian Press was first published June 29, 2020.

Shawn Jeffords, The Canadian Press